1. Field of the Invention
This invention generally relates to integrated circuit (IC) fabrication and, more particularly, to a system and method for forming silicon dioxide films overlying a silicon carbide substrate,
2. Description of the Related Art
The silicon-based (silicon substrate) MOSFET is the most commonly manufactured electronic device, worldwide. However, Si-based devices, including MOSFETs, fail under extreme operating conditions, such as high temperature, high power, and high radiation. There is a growing interest in semiconductor materials and devices that can be used in high temperature, high power, high frequency, and radiation hard applications. Silicon carbide (SiC) is a promising semiconductor for these electronic applications because of its wide energy bandgap, high saturated electron velocity, high thermal conductivity, chemical inertness, and high breakdown field strength. Rapid advances in the growth, doping, and the processing of SiC have led to the realization of several electronic and photonic devices that use SiC substrates, including fast recovery high voltage diodes, metal oxide semiconductor field effect transistors (MOSFETs), metal semiconductor field effect transistors (MESFETs), static induction transistors (SITs), junction field effect transistors (JFETs), and UV photodiodes. The wide bandgap and high thermal conductivity are attractive for high temperature digital integrated circuits and nonvolatile solid-state memories. SiC bipolar devices, bipolar junction transistors (BJTs), and hybrid bipolar transistors (HBTs) have application-specific advantages, as compared to Si bipolar devices. Higher doping can be used for SiC devices, resulting in a smaller on-resistance that is due to the higher breakdown field strength of SiC.
A remarkable property of the SiC is that it has a native oxide-like Si. SiC can be thermally oxidized, like Si, to form SiO2. However, SiC MOSFET performance is hampered by a high density of interface states. As a result, carrier mobility is significantly reduced and the current (power) handling capability of these devices is much lower than would otherwise be expected. The thermal oxidation of SiC is typically carried out at temperatures in the range of 1000–1300° C. This high-temperature thermal oxidation process can be harmful to some conventionally used IC materials such as glass or plastic. However, oxidation at lower temperatures conventionally requires excessively long oxidation times.
It would be advantageous if a high quality silicon dioxide layer could be formed overlying a SiC substrate at a relatively low temperature.